Telephone-exchange system



Sept. 2. 1924. 1,506,864

L. POLINKOWSKY TELPHON E EXCHANGE SYSTEM Filed hay s. 1919 2 Sheets-Sheet 1 Sept. 2 .-1924. Y 1,506,864

l L. PoLlNKowSKY TELEPHONE EXCHANGE SYSTEM Filed May 5. 1919 2 shams-sheen 2 ,man 235 l 229` 247%- l 2274 z'zje21 224; :Y V J U, 4L i by MMM] Patented Sept. 2, 1924.

UNITED LIPA 1 0LINK0WSKY, OF, vNEW YQRKHNuLYfQ.ASSIGNQW PANY, INCORPORATED, '0F NEWYO'RK, `1\T .Y.,YA CORPORATION 0F NEW YORK.

To all @0.7mm t may concern:

Be it known that I; Lira' Poiimiioiysir, a citizen of Russia 'residing at New York, in the county of eiv Yori; and State ot' New York, have ini'ffented certain new and useful Iiiiproyeinents -in Telephone-Ez'r-- change Systems, 'of which the folloy'ving` is a full, clear, concise, and `exact description;

This rinvention relates to Itelephone systenis. employing machine Syyitchiii'g appa` iatus for setting up connections between subscribers" lines.

More particularly, it relates toa riiachine switching' telephone system in which party line Working is invelyed, 'the several sub scribers .stations `on. a I party line `"being equipped 'Witli calling and switch-controlling devices Wliereby a callingjsubsciibei may 'control the operation of automatic switches in the exchange to extend his line into connect-ion with any. other subs'ciibers, line. Further, means are proyidedat` each sub-y station whereby a fc'alliiitg'I vsubscriber bn a..

party line, desiring-to li'oldl' c'oiiyersatioii with another subscriber oli the saineA line, inay so Control the operation fof the aiito matic switching apparatus at the exchange that a talking foiine'cti'oii is'establish'ed be'- tween the calling and called sulostations dii vthesanie party line. Y

ALn object fof this invention tliepro'-v Vision, in addition tb the regular 'linefind ers aiid l'selectors aty 'the exchange used in establishing a connection betWeentWo different, Suljscribers lines; of ai plurality tof special line linders which may be taken for use to complete a talking' connection iyhen'-l ever a subscriber on a pa1ty-line'desiresto converse with another subscriber on the same party line. Y f A feature of invention, in asystein character employing special lline v iiideis for revertir@ calls, consists inthe arrangement of the line relays such that act Qta. callingl subscriber in initiating a regular lcall causes the operation' ot an vordinary line finder, Whereas' the act of ,initiating aie/.e'r

tive call is Without eii'ect to start sucliiinder, but serves instead to initiate the operation Aof another findery used especially for rayer-` tive connections.

i further featureisthat by theuse of 191e. sei-iai N. 294,738: Y

these special lihe finder stvit'chsfor rever- I tive calls it is not'eessar'y tor the-refilling Isubscriber to manipulate his `callin; `devi'ce finders for reyertive calling, which when g one of suchv finders isA appropriated 'may be;

operated toapply the'propei-eharacter of ringing current back upon the line, therebyl ringing the bell ot' t'hevcalled. substation.

A still further feature of the invetio'n-residesin anautoinati'c releaseinechanisn'i provided in common to a vplural-ity:ofV `tinder switches, andgparticiilarly appli-cable to above desc-ri'bedtype of ndersforrevertiife callijn'Z'g",` whichl becomes reffe-tii'rev at the proper time to release anygiinde stvitch that irregulark manipula-tion? of the substation apparatus, er for 'any otherl reason liasnot completed ,its regular 'pera-tion; ASi

'Such other and further` eatuiesfas Para contemplated by the present iiix'gentionaw become clearly'apparent trointhe followingi description and appehdedtlairns;

vhas been 'taken for' usebut Whi'h' diie to. the subscribers abandnmeit fof the call; .an

g In' tli'e drawing, which. forinsa part of this applicationg/Figll shov'ysa party line having four v.substa'tions thereon, aiid termi# nating' in the exchange 1n the multiple terniinals or final selectors, the ordinary line iinders and the speeial line-finders luscli'foi'ythe purposeV otihaking revettiveralls; Fig. 2 vshows in' detail the circuit arrangiiient of 'one of the special-line finders',l There is also' shown a releaseirnechanism' adapted to bey associated Withfa-pliirality of line finders.

it is believed that the invent-en-ivi1ibef best understoodv troni avv description ot' the ope'iatioii"oi" the system in which the saine embodied. ,A l

Referring tothe drawin s',-each substaf eqn .on the party une' is. prevista with the yusual equipment includingthetransmitter,

receiver, calling dial, ringenet'c; Iii additibia, there' is' further provided a, ly 292 for use in making revertive calls, and additional condensers 294 and 295 and a key 296 to be used for revertive ringing. The party line is connected in the exchange to four sets of terminals such as 270, 271, 272 and 273 in final selective switches. By arranging these terminals in two separate groups of' final selectors, each substation on a party line may have a separate number in the exchange which enables the selection of a proper kind of ringing current. The party line also appears in terminals 210, 274 and 276 of an ordinary first line finder such as that diagrammatically illustrated at 277, and further in the terminals 250, 258 and 275 of special line finder switches such as the one shown in detailin Fig. 2 used only when a revertive call is made. Each subscribers line is provided with two line relays-201 and 202. Relay 201, when operated, serves o start the operation of idle first line finders when a callis made' from one subscribers line to another subscribersline. Relay 202 is difstation apparatus for making a revertive call to start ink operation the spexial line finder switches. f

Assume first that a subscriber on the party line shown desires to converse with the subscriber at substation 285 on another line which may be either a party line of an ordinary subscribers line. On removing the receiver from the switchhook, al circuit is established from battery through the righthand winding of line relay 202, back contact and outer armature of cut-off relay 207', over the lower side of the line, through keys r292 and 296, dial 293 and thence over the switchhook to the other side of the line and returning over the innervarmature and contact of relay 207, through the left-hand winding of relay 202, winding of relay 201 to ground. Current flowing in this `circuit is without effect to operate the differential relay 202. Relay 201, however, attracts its armature and closes a circuit from battery, through the inner windings of starting relays 204, over the armature and contact of relay'201, to the terminal 210 of all regular rst line finder switches having access to the group of lines to which the calling line belongs, thus placing a selectable condition uponsuch terminals. The armatures of relays 204, by closing on their contacts, complete a circuit in the well-known manner for the powerfmagnets of all idle first v'line finders suchV as the Aline finder 277, which thereupon begin to move in search of the calling line. Line finder 277 on finding the terminals' of" the calling line, operates to initiate the movement of a second line finder 273 which extends the connection to a selector 279. The subscriber then manipulates his dialY 293 to further extend the connection over selector 279 and final selector 280v to the called line. The finder and selector switches used in establishing a connection between subscribers lines may be of anyapproved type such as 'the switches disclosed in the patent to Polinkowsky No. 1,193,053, patented August 1, 1916, and need not be described in detail herein.

it will now be assumed that it is desired l/Vhen lthe from battery, through the right-hand winding of relay 202, contact and outer armature of relay 207, over the lower side yof the line to ground at the contact of key 292. Current fiowing in this circuit serves to energize the differential relay 202 r`which attracts its armature and completes a circuit from battery, through the right-hand winding of said relay, contact and outer armature of relay 207, armature and Contact of relay 202 to ground through the winding of starting relay 203. Relays 202 and 203 are thus energized in series and relay 201 being shunted, does not operate when its circuit is closed by the release of the revertive calling key 292. The regular line finders are therefore not started in operation. Relay 203 completes a circuit from battery, over` its right-hand armature and contact of relay 203 to place aY selectable potential upon the terminals 250 of the special line finder switches. A circuit is also closed from ground, over the armature and contact of relay 203, armature and back contact of test relay 212, through the winding of power magnet 211 to battery and ground at the sequence switch contact 215 bottom. This circuit being multipled to the power magnets of' all finders in the group, 'such finders as are idle at this time will be started to search for the calling line. rotate, and the first finder arriving upon the terminal 250 completes a circuit from battery, through the armature and contact of relay 203, terminal 250, through the rightiio The brush carriages n hand high resistance winding of test relay 214, to ground at contact 216 of sequence switch 220. Relay 211i operates and closes a circuit in parallel to its right-hand. wind ing which includes the low resistance left'- hand winding of such relay and the second test relay 212. The low resistance of this circuit so reduces the potential on terminal 250 as to render the calling line non-selectable to other finders.- Relay 212 by operating', opens the circuit for the power magnet 211 which brings the brush carriage to rest. A circuit is also closed over the front contact of relay 212, sequence switch contact-217 i switch'220, av circuit vis closed? troin battery,y

substation loop and returning overthe'upf bottom, to drive .the 'sequence siivitch 220 out ofposition k1 and intor position fl; i

The sequenceswitch contact 216, fin pass# ing out of V4position 1, opens'fthe'en'ergizing circuit of vthe high resistance Windingojt' test relalyr214'. Inposition3 ot'sequence through lthe left-hand Winding of relay 222, sequence switch contact 21'(- top, froiitcon-` tact and armature of relay 212 vto ground at the left-hand armature of 'relay 203. Relay' 222 operates and 'closes- "a circuit yfrom ground, over sequence 4switch coiitact7216v top, arinature land front Contact and righthand Winding of relay 222, terminalv 258, through lthe Winding of cut-ofi' 'relay-2:07 to battery and ground.y Cutoli' relay 207 op-r erates and relay 222 remains energized in this circuit. Tjhecut-off relay, by operatf ing, opens the circuit of line relay 202 and starting relay 208 Vwhich are thereby decir erg-ized; '.,Other searching-line in'dersfaie broughtA to rest at this time. Y

When sequence switch 220 reaohes'posil tion 4, a circuit is comple-ted from battery, through the secondary Winding' of the dial tone coil 224, contactf213 top, right-'hand armature and back Contact of relay 226', bac-l Contact and left-lian`d 'armature of relay 227 over the lowerv Side of the line, through the' per side of the line through the right-'hand armature and back Contact of relay 227, left hand armature and back ,contactot relay 226, sequence switch contact285 top, through the Windingr of the stepping relay`229 to gi'ou1id. Relay l229 energizes and closes a' circuit -from ground, through 'its armature and front Contact, armature and back' 'conn-i tact of relay' 223, through the Winding of relay 231-to battery and ground.Vv Relay 231, by attracting its armature, closes a circuit over Contact 21,9ftop -to drive the se-` quence lswitch 220 outof position 4. through positions 5 and 6 into position S. On reaching position 8, contact- 215closes an'energizing circuit Jfor rela.yf223 including the armature and back contact of.relayf232."

' The register 100, individual tothe finder sivitcli and which is, operated under the control ot tl'iecalling substation to apply ringing current of tlie'prop'er character 1back upon the callingline, is now moved out of position zerol by a ycircuit :t'ioin battery, through the Winding of register 100,'contact 22S bottom, contact andl armature and lefthaiid Winding ot differential relay 239, front contact and armature of relay 223, to ground at the armature of relay 229'l The register 100, leaying position zero, closes a. circuit to' groundat its local contact 101, thereby shuntingithe left-hand Winding ot differential relay 239,. so that this relay is `new energized in series With the retardation coil 233.V egister 100 moves into position A1 Wliiieii, @mestorest' The primary-Winds" i ingjof thedi'al tone coil 224 is` connected over. contact-108 With,v the interrupter 2115..

The calling subscriber hearing the ,dialing` tone, operates his dial 293 for one digitcorresponding tothe designation ot yt-hesubstation Wanted lon the saine party line. At

the lirst interruption, theline relay 229 de y energizes and opens the ycircuit tliroughth'e right-hand Winding of relay 239, which also deenergizes. -WVhen the tline is again closed at'the end- 'of'I` the first impulse, the circuit" y' for thefright-haiid winding of relay 239 is closed'and at the saine time thel above tracedr t circuit vincluding "sequence switch" winding andthe letti-handivinding of differential relay 239.v Relay'239 remains inactive and theregister 100 starts from positioiil.v

Onleaying positiony 1, the lett-'hand Wiiid` ingoi` relay 239 is shunted at thetl'ocal v'contact 101, fand relay 239 'thereby energizesf Atthe same instant, a circuit is completed from battery, throughthe Winding `of relay 237, contact- 228 bottom cto ground at the local Contact 101. 'Relay 237.closesat its armature Aa circuit to-ground for the righthand winding ot relay 239, independent ot the ground at "relay, 229. This insures that the relay 1239, once operated, will retain its armature until the register 100 has taken 'a full step -and'op'ened the Circuit ttor relay 237y which occurs as soon as said register reaches Y position 2. 71th the relay 237 deenergized in positionv2, vwhen ,the subscriberlsl line is open on the second impulse, the right-hand Winding of relay 239 deenergizesonce morel and'hsaid relay releases its armature.. This operation 'continues and the register 100 advances one step foreach interruption caused by4 the,callingsubscribers dial. `Each time therelayi 229`retractsits armature, a inoA mentary circuit isjclosed for'` relay-234, oyerf sequence switchc'ontact 236; but this relay,

being constructed to 'energize slowly, cloes not operate atfthis time; However, on the lastinteriuption caused bythe subscribers.

dial, the line is opened `for. a coriiparatively vlonger `interval which enables the relayQSsl `to become energized. A circuit is'tliereupoii l completed-'freinground, over the armature andcon'tact ot' relay 234, sequence switch contact 22113 bottom, through thefright-hamli- Winding of relay232 tobattery and ground.v 4 The energization ot relay 232 closes av ciry K f cuit froinbattery, through the Winding;jojiz` sequenceswitch magnet 220,v armaturerand,

back contact jot-relay 231,contact--218top,

left-'hand Winding, front,` contact and arma- Atiirefof relay 232,1l to ground, Acausing `said in series Withthe'line for a sufficient time.

to.,perniit tliedeenergization otrelay 234.

Relay 234, in "releasing its; arniatuie,vopeiis relay will deenergize and open the above traced circuit which started sequence switch 220 out of position 8.

The calling subscriber now depresses the revertive ringing key 296 which brings the small condenser 294 in series with his telephone and also opens the circuit of the substation to the flow of direct current. The line circuit, being thus opened, relay 229 deenergizes and at its back contact closes a circuit for relay 234 over sequence switch contact 236 top, which in turn energizes and closes a. circuit over sequence switch contact 243 top for the energization ofthe righthand winding of relay 232. Relay 232 again energizes and closes the above traced circuit including sequence switch Contact 218 top and the armature of relay 231 to drive sequence switch 220 out of position 11 and into position 12.

As was previously mentioned, the termi-A nals of party lines Vare arranged in two groups ot' final selectors in the exchange. By this arrangement, when a call is established between two different lines, which operation involves the use of aiinal selector switch, these selectors, by connecting the called line over one or another set of terminals rin which it appears dependent upon the designation of the party desired, are effective to apply ringing current of the proper character to ring the bell of the called substation. For this purpose, alternating ringing current superimposed upon direct current oi' different polarities may be used for ringing the desired bell. Since each tlnal selector is provided with 200 terminal sets7 the four stations of the party lines could have numbers varying only in their hundreds digit.

lVhen a revertive call is made, and Aonly one digit is dialed for selecting the properl kind ot ringing current this digit may correspond to the hundreds digit of the party line number. The register is arranged to provide the required connection for re,- vertive ringing in positions 6, 7, 8 and 9, which correspond to the dial-ing of numbers a, 3. 2 and 1'. According'to the position in which register 100 stands, either the relay 226 or relay 227 is energized in acircuit over the back contact of relay 230 and sequence switch contact 238 top. 1f the digit 1 or 2 has been dialed and the register 100 is in position 9 or 8, the relay r227 will be energized. This circuit is traceable Afrom battery, through the winding of said relay, contact 103, back contact and armature of relay 230, contact 238, to ground, whereas, it the digit 3 or 4 has been sentand the register stands in positions 7 or 6, the relay 226 is energizedv in a circuit from battery,-

through the Winding 'of said relay, sequence switch contacty 107, back contact and righthand armature` of relay 230, contact 238 top to ground.

An alternating ringing current superim-` posed upon direct current sent over the party line. In case the digit 1 or 2 was sent, i

and relay 22-7 energized, the ringing circuit leads from the alternating current source,

over either the contact 109 or 110 dependentl upon thedigit, front contact and left-hand armature of relay 2,27, to the lower side of the line, through, the ringing relays 297, 298 and l299 of the other threevsubstations, back over the upper side ofthe line, through the right-hand armature and front contact of relay 227, windingof relay 240 to ground at the left-hand armature of relay 230. Only the ringer at the desiredstation is operated.

ln case the digits 3 or 1 were sent, and relay 226 energized instead of relay 227, the ringing lcircuit is traceable from the alternating i tour substations maybe Selected and rung to the exclusion of the ringers at therem-aining substation. When the receiver' at the called substation is removed -from the switchhook, the resistance in series with the ringing confr trol relay 2110 being reduced, said rela-ybecomes energized and closesV a circuit from battery, through the right-hand winding of relay 230 to ground at :the armature of re-` lay 240. Relay `230 closes a locking circuit I over its right-handwinding to ground at the sequence switch-contact 238 top, and also opens the -circuit of, relay 240 and either releases relay 226 or 227 as' the case Imay be. The ringing operation is thereby terminated. The talking circuit is now completedand battery furnished to the line,

through the Winding of relay 231, sequence.

switch contact 213 bottom, right-hand armature and back contact of relay 226, yback` contact and lett-hand'anmature of relayv 227,k

over the line and returning by `way of the right-hand armature and backcontact of relay 226, sequence switchcontact 235 bot@ tom,ithrough the retardation coil 2217 to ground. Relay 231 energizingy closes acircuit over sequence switch contact 219 top to drive sequence switch 220 out of position12 and through the intermediate positions, coming to rest in position 18.1 -A circuit is above described, the ringer at any one ot they V1 02 bottom and contact238 bottom to move said register intoV its'v vzero position.

After the conversation is completed and the receivers are replacedfon the'hooks at b oth substations, the relay 231 deenergizes and lcloses a circuit including sequence switch contact 219 bottom, to. drive sequence switch 22,0 into position 1 On leavingv position 18, contact 216 opened the above tracedholding circuit for relays 222 `and 207, which thereupon, deenergize. The apparatus is nowrestored to normal ready to be operatedon the incoming of anothercall.

In. order to makethe switches in theexchange independent of an erroneous lmanipulation i of the substation apparatus, the special line nders used for revertivecalls have associated therewith an automatic release mechanism, which is common `to a: pluralityof such finders. This mechanism is so arranged that any line finden which has been started in operation by erroneousvactuation of the'` substation equipment Vwill be auto-4 matically restoredto. normal. after a reasonable time has elapsed.4 For instance, t he calling subscriber lmay hold the revertive calling key 2,92 depressed foran unreasonably longtime orhe ymay abandonthe call after havingonce vdepressed said key without removing thefreceiverfrom the switchhook; Relay 229, which`.dependsI for its energization upon a-closure of the line circuit, would not. be operated and consequently, sequence 1switch 220vwould not'be driven out o f position 4. To avoid the line being held busy in this manner, the common re-v lease mechanism including a sequence switch 260 is provided to, insure the restoration of all finders improperly moved from their normal position.. Vhen the sequence `switch 220` of `any one of the special line finders to which the automatic release mechanism is common reaches position 4, a circu-it iscompleted 'from battery, through the winding Thereby. 268, being differentialremains deenergizedf until sequence switch 260 closes a.. short circuit at the local contact 261 lfor the.right-handwindingof relay 268.l lRelay 268 now transiz.es 'and Opens the Circuit traced for sequence. switch 2 60 which .is arrested; as as it reaches; positions.

when the.. interrupts Qrefie the @mit ef prgvided. for register 1 00 including contact relay-264, this relay together with relay 268,

deenergiz'e's 4and'ithe circuit i for sequence switch '260 is again prepared. Eachtime the sequence switch 260 passes from posi-` tions 4 to 7, A10 to 1 3 or 16 to "l, la circuit is'teni'porarily closed over sequence switch contact 265, sequence switch contact 236 bot'- tom to causethe energization of relay 234.

vRelay 234 attracts itsp'armature and closes a circuit from ground, over its armature `and contact, sequence switch contact top," which it will be remembered is in position 4, leftlh'andwinding, armature and 'contact of relay 239, contact 228 top, armature and back contact of relay `231, through the winding' of sequence switch' magnet '220 to battery and ground. AvSequence switch r220 moves into lposition v5, and on closing itslocal contactbetween positions4 and' 5 shortcircuits'the left-handf'winding of differential relay -239 which :energizes and opens the ycircuiti traced for sequence switch 2:20until relays 239 and 234 are. a'gainxde# energized. Relay262 Aremaining' energized Jover contactv 242fin'position 5 of; s'equence switch 220,' sequence switch' 260 isadvancedl at eachiclosure of" the interrupter 269 'from one position toanother until contact l265is again closed in position ll Yof" sec'luence switch 260.1 .Relay 234 is again energized 'and sequence switch220 is moved o utfof position 5 'and into position 6fas abofve de-y .i maywhap'penthat sequence switch v"220 reaches positiponejust vbeforefcont'act l265 closed,- due'to a sequence switchofanother lineffinde'r being heldin a positionzin which frelay' 262 is energized. Sequence 'switch 220 .may therefore move overlpos'ition`4'imf mediately,fbut the sequence switch'is'detained*'in rits 5th or 6th positions-'for' a reasonable length of time to enable the calling 'subscriber to. remove the receiverifrom the hook and release the key 2,92. When .the

.sequence switch 220'leavesgposition 17, relay 262 remains de energized and said sequence switch stops when it reaches position l'. vItnnay` further happen that'thetcalled party doesV not reply, whereas 4.the calling subscriber while holding the key 296 depressed would give up the'call ancl.restore thenreceiver to the switchhook before re- In such la case leasing the ringing key. M theline would be opened at `the switchhook contact before it would. close at the key 296 and consequentlyvthe ringing. control relay 240 y remains deen'ergized. Sequence switch. 220,"againprovidesa connection to the common release equipment so. that 'said sequence, switch is, atfgi'ven time intervals advanced over its positions. 12, 13, 1.4[`15, 16am.. .17.. whelrbrtlle. iiieesioflthe Grilled stationy continues for a reasonable length of time, after which sequence switch 220 moves into position 18. Since the party line is open, relay 231 is deenergized and consequently a circuit is completed over the armature and right-hand Contact of said relay to ground atl the sequence switch contact 219 bottom to drive the sequence switch 220 out of position 18 and into its normal position 1. In restoring the ringing key 296, a calling subscriber is also enabled to give up the ringing vbut may continue to wait for a reply from the called subscriber.

If none of the ksequence switches corresponding to the sequence switch 220 are in positions 4L to 7, or 12 to 17, relay 262 is deenergized and a` circuit is establishedl to drive the sequence switch 260 into either one of its three starting positions 1, 7 or 13. This eircuit'includes therght-hand arma-ture and back contact of relay 262 and sequence switch contact 267.

The common release mechanism 4is also capable of releasing the .finder switch-where two vfinders have stopped on the terminal of the same calling line- Assuming that two finders reached the terminals of the calling line at the same time, two test relays 214 might become energized in parallel over the right-hand high resistance windings. Upon the sequence switches 200 of such finders moving out of position 1, and consequently, upon the opening of the circuit of the right-hand high resistance windings of the test relays 214., the current ,y

flowing in parallel through the circuits including the left-hand low resistance windings of relays 214 and the winding of relays 212 would be insufficient to maintain the energization of `both sets of these relays.

Consequently, the test relay 212fof one of such line finders wouldy be deenergized immediately upon the sequence switch -.220 leaving position 1. Therefore, upon the sequence switch 220 passing through position 3, relay 222 is not energized. Instead, how ever, a circuit is completed from battery, through the winding of relay 227, left-hand vwinding of relay 230, back contact and armature of relay 222, sequence switch contact 216 top to ground. Relay 229 and consequently relay 231, are maintained deenergized due to the `energization of relay 227, and the sequence switch 220, under the control of the common release mechanism, passes through its cycle of `operation as .above described. The connecting circuit of the line finder being held open at the contacts of relay 227, and the register 100 remaining in position zero, no interference is caused with the party line during the restoration to normal of a finder switch which has thus been improperly operated.

Whatis claimed is: 1.'In'a telephone system, a subscribers line, a pair of automatic switches having access to said line for establishing 'telephone connections, two line relays for said line,

one of which is dierentially wound, 'said relays being individual respectively to'said automatic switches, vmeans at the substation of said line controlled by the subscriber' in the act of initiating a call for selectively operating either of said relays, means responsive to one of said relays for operating the corresponding switch, and means responsive to the other relay for operatingl the other of said switches.

2. In a telephone system, a subscribers line, a pair of line finderswitches having access to said line, twoline relays'one of which is differential, said relays being individual respectively to said finders, -`means under the control of the subscriber in initiating a call for selectively operating either of the line relays and for rendering the other relay inoperative, means responsive to the operation of one of said relays for operating one of the finder switches, and means vresponsive to the operation of the other of said relays for operating the other finder Switch.` y i y 3. In a telephone system, a party line, another line, an automatic switch responsive t0 the initiation of a call lon said'party line,

means cooperating with said. switch for establishing a connection between saidlines,

a second automaticswitch responsive to the initiation of ka callon the party `line fory making connection with said party line, and

means under the control of the subscriber in initiating a call on they party line for selecting either of said'automatic switches for use.

In a telephone system,` a party linen, calling transmitters 'atthe substations on said party line, ringing devices at said substations, another line, selective switches for interconnecting said lines, line finders for automatically extending said party line 'to the selective switches, a groupl of special line finders for establishing atelephone connection between two ysubstations on said party line, means under the control of the subscribers in initiating a call on the party line for selecting either said first r'nentioned l yfinders or saidspecial finders, a source oi ringing current associated with the special finders, and means under the' control ofV said calling transmitters for Yapplyingsaid sourcetothe party line to 'operate the ringiiigdevice at a called substation. thereon.

5.v In a telephone system. a subscriber`s line, two groups of automatic switches,said

switches being re'sponsiveite the initiationi of a callv on said line to establish a telephone connection, means under the control'of the subscriber for selecting for use the switches of yeither group, a release mechanism *for the switches of one ofsaid grou s, andmeans operative under the control o said mecha-- nism for releasing any switch ofsuch group that has been started in operation.

6. In a telephone system, a subscriber-s line, two groups o't` automatic switches, said switches being responsive to the initiation `of a call on said line, to establish a telephone connection, means Linder the control of the subscriber for selecting for use switches of either group, a release mechanism common to the switches ot one of said groups, and means operative under the control of said mechanism at the end of aldefinite time interval after any of suchswitches have been started in operation for restoring the same to normal.

7. In a telephone system, a line iinderl switch, al telephone line'having a plurality of substations thereon, said line appearing in terminals of the yfinder switch, means responsive to the .act of initiating a call at one of said substations for operating the finder switch to'make yconnection with said line, a talking battery for supplying current for the talking connection between said substations, and means at the finder switch individual thereto and controlled over the lineafter said switch has operated for connecting said battery to said line.

8. In a telephone system, a linev inder switch, a telephone'line having a plurality ot' substations thereon, means responsive to the act of initiating a call at one of said substations for operating said finder, an auXiliary controlling switchv for said finder, a talking battery for supplying current for the talking connection between calling and called Vsubst-ations on said line, and means controlled by said auxiliary switch for connecting the talking battery to said line.

9. In a telephone system, a party line, a line finder switch, means responsive to the initiationl of a call on said party line for operating saidfinder, a source ofringing current, and means at said finder switch controlled by a calling subscriber for variably connecting said source of current to the party line tof selectively signal the substations on said line.

10. In a telephone system, a partyl line, a line finder switch, means responsive to the initiation of a call on said party line for operating said finder, a plurality ofsources of ringing current of different character, and means at said finder switch controlled by a calling subscriber for variably connecting said sources of current to the party line to selectively signal the substations on said line.

' 11. In a telephone system, a party line, a line finder switch, calling transmitters at the substations on said line, means responsive to the initiation of a call on-the party line for operating said finder, a'source ofringing current, and means at said finder switch controlled by the calling transmitters forv variably connectingsaid source of current to the party line to selectively signal 4they substations on said line. 12. In a telephone system, a party line, calling transmitters at the substations on said line, means responsive to 4the initiation of a call on the party line for operating said l inder to establish a talking connection be tween two substations on said line, a source Y.

vof ringing current, Aa register at the said linder switch, means controlled by said transmitters for' variably setting Said register, and means dependent vupon the setting of said register for varia-bly connecting saidsource of current to the party line" to selectively signal the'substations on said i line. c

13. In a telephone system, a party line, calling transmit-ters at the substations on said line, ringing devices at said substations, another line,selector switches for interconnectingsaid lines, line finders Jfor automati-V cally extending said party line to the selective switches, special line finders for establishing a telephone connection. between two substations on said party line, means" under the control of the subscriber in the act of initiating ya call yori/the party y line 'for selecting either saidffirst mentioned finders orsaid special finders, a source of ringing current, a register.I device individual to each tween two substations on said party line,

means under the control of the subscribers in initiating a call on the party line for selecting either said irst mentioned linder or said special finder, a source of-ringing current associated with the special'iinder, means under the control of said calling transmitters for applying said source of current to the party'line to operate theringing device at a called substation thereon, atalking battery for supplying current for the uio talking connection between twol substations on the party line, and means at said special finder switch for connecting saidr talking battery to the party line. -v

In witness whereof, I hereunto subscribe my name` this 29th day of April A. 1919; v i 'f i y"LIllA 

